Apparatus for delivery of predetermined amounts of molten metals to a die casting machine



F. L. BURKETT May 3, 1966 3,248,759 F MOLTEN APPARATUS FOR DELIVERY OFPREDETERMINED AMOUNTS O METALS TO A DIE CASTING MACHINE Filed March 28,1965 2 Sheets-Sheet l INVENTOR. F ranc/s L. Burke/2 HTTOQNEYS y 3, 1966L. BURKETT 3,248,759

APPARATUS FOR D V 0F PREDETERMINED AMOUNTS 0F, MOLTEN MET S TO A DIECASTING MACHINE Filed March 28, 1965 2 Sheets-Sheet 2 I I [A 54 46 I 4046 I ?;0

INVENTOR. Franc/Is L. fiur/ns WJMA HTTOR/VEYS United States PatentOffice APPARATUS FOR DELIVERY OF PREDETER. MINED AMOUNTS F MOLTEN METALSTO A DIE CASTING MACHINE Francis L. Burkett, Breckenridge, Mich.,assignor to The Dow Chemical Company, Midland, Micl1., a corporation ofDelaware Filed Mar. 28, 1963, Ser. No. 268,632 1 Claim. (Cl. 22-79) Thisinvention relates to the handling of molten metal and particularlyconcerns an apparatus for the delivery of successive predeterminedamounts of a molten metal to a utilization device.

A great number of apparatuses have been disclosed concerning thedelivery of measured amounts of molten metal to a die casting machine.In general, each of these devices comprise one or more separate butconnected components, such as, for example, a valve assembly and arotory pump, one of the so-connected components in turn being attachedto a heated delivery pipe. In addition, these devices are relativelycomplex, having usually a number of moving parts, many of which requireclose tolerance dimensions for proper operation.

Because of these factors, malfunctions and breakdowns arefrequent, thusrequiring a high level of maintenance and experienced operatingpersonnel. Also, a complex apparatus consisting of several separateassembles but connected to one another by various conduits isunderstandably more difiicult to install and to remove from the supplypot of molten metal in which it is partially or wholly submerged shouldthe apparatus need repair or replacement.

An object of the present invention, therefore, is to provide a simpleand economical apparatus for the delivery of a succession ofpredetermined substantially equal amounts of molten metal to, forexample, the shot well of a die casting machine.

Another object of the present invention is to provide an apparatus forthe delivery of a succession of substantially equal amounts of moltenmetal, having a compact integrated pump-valve unit which is readilyremovable from the molten metal supply pot in which said unit issubmerged.

A related object is to provide such a unit having a minimum of partseach of which are readily replaceable.

A further object is to provide an apparatus for the delivery of moltenmetal which will require little main- 7 tenance. I

Yet another object is to provide an apparatus for the delivery of moltenmetal which during operation will not cause turbulence in the potcontaining the supply of the molten in which the apparatus is partiallysubmerged.

These and other. objects and advantages will become apparent from thefollowing detailed description when read in conjunction with theaccompanying drawings which depict one embodiment of the inventionwherein:

FIGURE 1 is a side elevational view, partly in section, of an apparatusin accordance with the present invention.

FIGURE 2- is an enlarged view in side elevation, partly cutawayandlargely in section, of the integrated pumpvalve unit of the apparatusof FIG. 1 taken along the line 2--2 of FIG. 3.

FIGURE 3 is a view of the integrated pump-valve delivery unit of theapparatus of the present invention taken along the line 3-3 of FIG. 2.

FIGURE 4 is a cross-sectional view of the control rod and valve stem ofthe integrated pump-valve unit of the apparatus of the present inventiontaken along the line 44 of FIG. 2.

Eatented May 3, 1966 FIGURE 5 is a detailed side elevational viewshowing a modification of the connection of the lip of the pot with theapparatus of the invention from that shown in FIG. 1.

The apparatus of the present invention is used in conjunction with amelting or supply pot containing the molten metal intended to behandled, the apparatus being partially submerged therein. The pot isequipped with a suitable means to maintain the metal therein in a moltenstate by the application of heat, and is either open -or closed at'thetop as desired.

In general, the apparatus comprises, (a) an integrated pump-valve unitcomprising a valve assembly portion and centrifugal pump portion, (b)one or more support members which provide a means to suspend said unitin a supply of molten metal, (c) powering means such as, for example, anair motor for said pump portion ((1) motion means, such as, for example,a reciprocating device for actuating said valve assembly portion and,(e) a delivery pipe to which the unit is attached at the valve assembly.

The pump portion of the above-integrated unit comprises in general, (a)a rotatable impeller as the core element surrounded by a'pump casingwhich in addition houses the valve assembly, said casing having both aninlet and outlet means to receive and dispense molten metal when theunit is in operation.

The valve assembly portion of the integrated unit, housed by the pumpcasing, comprises in general, a stationary but replaceable circularvalve seat, and a movable conical or round headed valve member capableof engaging the valve seat to form therewith a substantially tight seal,the movable member being connected to the above motion means foractuating said movable valve member in conjunction with the operation ofthe pump and with the receptacle of a utilization device for receivingthe delivered molten metal such as, for example, to the shot Well of adie casting machine.

Referring now to FIGS. 1 and 2, one embodiment of the apparatus of thepresent invention is shown therein, the integral pump-valve unit 10 ofthe apparatus being suspended in a supply pot 12 containing molten metal14 by vertical supports 16 which are attached to horizontal crossmembers 18, the cross members being in turn attached to the lip 20 ofthe pot 12 by bolting. Alternatively, said cross members may also beattached to the lip of the pot by freely removable locators 19 as shownin FIG. 5. As depicted the pump portion of the submersible integratedunit 10 comprises an impeller 22 attached to the lower end of a verticaldrive shaft 24 which extends upward through the said casing, describedbelow, and out of the pot 12, said shaft having a longitudinal axiscorresponding to that of the pump casing, and is attached at its upperend to a powering means, such as, for example, an air motor 26, which isdetachably mounted on the aforementioned cross members 18. In addition,surrounding said impeller 22 is a two-piece pump casing comprising a topportion 28 and a bottom portion 30 held together by threaded bolts 32from the upper side 34 of the unit 10 which are received by tappedthreaded bores 36 in the bottom portion 30 of the assembled casing toallow the two said portions to be drawn together and sealed tightly attheir mating edges 38. Other conventional fastening means, however, mayalso be used to hold the said pump casing portions together. A bushing40 designed to preferentially wear with respect to the drive shaftprovides a seal between said drive shaft 24 and the top portion 28 ofthe pump casing through which said shaft extends.

Attached to the underside 42 of the assembled casing is an extendedinlet, having a continuous Wall 60 to form an inlet part or opening 44,for receiving molten metal,

located such that the vertical (longitudinal) axis of the circularshaped inlet opening 44 of the inlet extension ultimately formed by saidwall 60, as hereinafter described, corresponds to that of the impellerdrive shaft 24. This specified correspondence of the axis of the inletopening 44 and shaft with that of the valve stem 52, described below,provides a liquid metal inlet 44 designed to avoid turbulence outsidethe pump casing which could cause undesirable entrainment of sedimentfrom the pot bottom.

In addition, the above described pump casing houses the aforementionedvalve assembly which comprises a circular valve seat 46, having abeveled edge 48, said seat being located in the hereinafter describedhemielliptical shaped part of the top portion 28 of the pump casing andresting on shoulders provided therein, being held therein by a closetolerance friction fit, and a movable valve member consisting of a valvehead 50 and a detachable stem 52, the head being adapted to mate withand engage the valve seat 46 to form therewith a tight seal without asticking or wedging effect. The stem 52 of the movable valve member, asshown in FIGS. 2 and 4, is attached to an essentially verticallyactuating control rod 54 by a spacer block 56, for example, by welding,such that when the control rod is actuated the valve head 50 and stem 52move accordingly.

The movable valve member when inside the housing provided by both theassembled pump casing and the continuous wall 60 of the extended inletis held away from said casing and wall and positioned, in conjunctionwith the control rod 54 and the aforementioned motion means, forexample, an air operated reciprocating piston device 74, for properengagement with the valve seat 46, by two (or more) spacer elements 58.These spacer elements 58 are attached to the curved part of the wall 60of the hemielliptical portion, hereinafter described, of the inletextension and located between said wall and the valve stem 52, thelongitudinal axis of said spacer elements, if extended, passing throughand intersecting at an acute angle at the longitudinal axis of said stem52 whereby the movable valve member slides on said elements and is heldin proper alignment with said spacer elements 58 and the control rod 54attached to the aforementioned motion means.

In general, the shape of assembled pump casing and inlet extension needonly be of a configuration sufficient to enclose the pump impeller 22and valve assembly and to provide an adequate inlet opening or part 44,as will be more fully described below, to receive molten metal.

A convenient shape to accomplish the above is shown in FIGS. 2 and 3.Specifically as illustrated in FIG. 2 the shape of the pump casing,commencing at the upper or top side 34 thereof, generally is of ahemispherical shape on one side of its minor axis and of ahemielliptical shape on the other side thereof. Looking at the whole onvarious successively lower planes (FIG. 2) the side wall of thehemispherically shaped portion continues uniformly downward ending andthe underside or bottom 42 of the assembled casing, whereas, the sidewall of the hemielliptical portion continues downward toward thevertical (longitudinal) axis of the assembled pump casing and endingalso at the underside 42 of the assembled thereof.

The shape of the extending inlet commencing at the underside 42 of theassembled pump casing and normally stepped in from the edge thereof isalso a hemielliptical and hemispherical shape, the wall of thehemiclearance between the inlet side wall 60 and the valve stem 52,which extends therewith, to permit an adequate supply of molten metal toenter said extended inlet.

The hemielliptical shaped portion of both the pump casing and extendedinlet side wall 60 serves not only, in conjunction with thehemispherical portion, to partially house the impeller 22, but alsoserves to house the aforementioned valve seat 46, valve head 50, andstem 52 thereof, said seat, head, and stem being aligned on a commonlongitudinal axis which is inclined at an acute angle with respect tothe longitudinal axis of the pump casing. It should be noted here thatthe inclined longitudinal axis of the seat, head, and stem crosses thelongitudinal axis of said pump casing at or near the inlet opening 44and that the valve stem 52 extends out of said inlet opening withsufficient length to allow coupling, through a spacer 56, to the controlrod 54, and with sufficient clearance with the inlet side wall 60 toallow operation of the valve assembly and influx of molten metal.

To the above described integrated pump and valve unit is connected adelivery pipe 62 equipped with a heating means, for example, electriccoils 64, to maintain said molten metal in the pipe in that state. Thelower end of the pipe 62 is attached to the upper side 34 of theintegrated unit 10 and surrounds an outlet bore 66 leading from thevalve seat 46 located in the hemielliptical shaped portion of the pumpcasing. The discharge end 68 of said pipe 62 is constructed andpositioned such to direct the flow of molten metal, when the apparatusis operated, to the intended molten metal utilization device, such as,for example, the aforementioned die casting machine 76 and shot well 78thereof.

It is to be noted that both the delivery pipe 62 and the aforementionedcontrol rod 54 are to be positioned such that they do not obstruct withone another. Preferably, the delivery pipe 62 is equipped with a slipjoint 70 located near the integrated pump-unit 10 so that should itbecome necessary to withdraw the integrated unit 10 entirely from thesupply pot either for replacement or repairs, the pipe is easilydisconnected therefrom leaving only a short portion of said pipeattached to the unit 10.

In general, the design of said slip joint 70 connection, as is mostclearly illustrated in FIG. 2, comprises two circular rings, eachattached to the adjoining delivery pipe Wall and each having a conicalmating surface capable of engaging the other, said surfaces each havinga low angle of engagement, for example, from 5 to 6 degrees, to cause aslight seizing action when mated. The rings are constructed of materialspossessing higher strength than that of their adjoining delivery pipewalls so that said rings will retain their shape even at the elevatedtemperatures normally employed or required in operation of the apparatusin the molten metal intended to be handled. By so-constructing the ringsany deformation due to elevated temperature will occur in the adjoiningwall rather than in said rings thereby making it possible to keep atight fit at the slip joint regardless of how many times said slip jointis disconnected and connected. A suitable material from which toconstruct said rings is the high temperature steel commonly referred toas Stellite, which is defined hereinafter.

The discharge end 68 of the delivery pipe 62 is preferably equipped witha hinged upwardly swinging hood or shroud 69 in which is maintained anatmosphere of non-oxidizing gas, such as, for example, sulphur dioxide,or argon, in order to prevent burning of the material and formation ofan oxide skin on the pipe walls. Said shroud cover 69 at the dischargeend of the pipe is constructed so as to freely swing clear of said pipe,as shown by the dotted lines in FIG. 1, of the end of the discharge pipeto permit cleaning when required and insertion of rods into the deliverypipe, if necessary, to unplug it.

Conventional air or electric motors may be employed as powering meansfor operating the impeller 22. For convenience and ease in removing saidpowering means from the balance of the apparatus, the armature thereofcan be, for example, quick-detachably coupled to the drive shaft 24.

The motion means for actuating the control rod 54 and valve head 50 maybe any conventional or other means whereby said rod and head may besufficiently moved to open and close the valve assembly to either allowor restrict the flow of molten metal therethrough. Such means may be,for example, a reciprocating air pressure operated device 74 toessentially vertically move the control rod 54, head 50, and stem 52 upor down longitudinally with respect to the longitudinal axis of thevalve. seat 46. Regardless of the actuating means employed a quickdisconnecting means (not shown) between it and the control rod 54 isalso preferably used for convenience in removal of the device 74 forrepair or replacement, or for removal of the control rod 54 from saiddevice 74 for similar purposes.

Preferably the motion means is coordinated either by air, electric, orother timing means 86, with, for example, the operation of the diecasting machine 76, such that a programmed time sequence is establishedwhereby a rapid succession of predetermined amounts of molten metal canbe dispersed to the shot well 78 of a die casting machine 76 or to someother molten metal utilization device.

In operating the embodiment of the apparatus of the present inventiondepicted in FIGS. 1 and 2 with a molten metal utilization device suchas, for example, a die casting machine, the integral pump-valve unitwith the delivery pipe 62 attached is submerged, after preheating, intothe pot 12 containing the molten metal 14 to be handled such that theentire integrated unit is below the level thereof but such that theinlet opening 44 is located so that the supply of molten metal is takenessentially from the center of the pot rather than, for example, fromthe bottom. By so locatingthe inlet, inclusion or entrainment in thecast article of settled residues is essentially avoided. The impeller 22is then continuously operated, at a rate of rotation so as to avoidexcessive surging or splashing when the valve assembly is opened, andthe valve head 50 disengaged from the valve seat 46 (to the positionshown by dotted lines) to allow molten metal to flow into the hotdelivery pipe 62 at least in an amount enough to fill said pipe to thedischarge level 80. When the desired level in the delivery pipe isobtained the valve head 50 and seat 46 are engaged to stop the flow ofmetal and maintain a proper head thereof in the delivery pipe. The diecasting machine 76 and shot well 78 thereof being ready to receive theinitial shot of metal, the valve is again disengaged from the seat andmolten metal allowed to enter the delivery tube in an amount previouslydetermined by proper timing and actuation of the valve control rod 54.The rate of rotation of the impeller 22 is adjusted so as to avoid toogreat a rate of molten metal flow resulting in splashing when dischargedinto the shot well 78. When said amount has entered the delivery pipeand has displaced a like amount from the pipe into the shot well of thedie casting machine, the piston 82 of said shot well, by means notshown, is then rapidly actuated to force the dispensed amount of moltenmetal into the mold cavity of the die casting machine 76. Aftersolidification of the dispersed amount of molten metal, the mold isopened and the cast piece ejected, followed by closing the mold, andoperating the valve head again to dispense still another shot into theshot well to produceanother cast article. The sequence is repeated inrapid succession by coordinating the whole operation to produce thedesired number of cast pieces.

Inasmuch as the integral pump-valve unit of the apparatus of the presentinvention has comparatively few moving close tolerance parts, necessarymaintenance will be 6 very low. With respect to the valve head 50, it ispreferably designed and constructed so as to preferentially wear ratherthan the beveled edge 48 of the valve seat 46. This is done because thehead can be more easily removed as compared to the seat by simplydisconnecting the valve control rod 54 from the motion means andlowering said rod with the movable valve member attached until the headof said member is removed completely from its housing. The worn valvehead is then replaced and inserted by reverse procedure back into itshousing. If, however, the complete integral pump-valve unit must bewithdrawn from the pot, this is accomplished by merely disconnecting thepowering means and the motion means from the cross members 18, removingthe delivery pipe 62 from the unit by disengaging the slip joint 70, andwithdrawing the entire integrated unit out of the pot. Substantially allof the molten metal in the pump will automatically drain out through theinlet opening 44 at the bottom of the pump. Any repairs can then beeffected, and the so-repaired unit preheated, resubmerged, andreconnected for operation, or, if a whole new unit is needed, it too caneasily be resubmerged and connected for operation. Time consumingchangeovers and repair procedures are thereby eliminated and theoperation continued without a costly shut down of the whole operation.To facilitate rapid removal of the integral unit from the pot forrepairs or replacement, rapid disconnecting means such as describedabove should be provided between the drive shaft 24 and powering meansand between the motion means and control rod 54.

For ease in accomplishing temperature determinations in the integralpump-valve unit of the present invention,

' one of the vertical support members 16 may be built with a hollow coreso that the wire of a thermocouple 84, for example, or other sensoryleads may be inserted therein and connected to the said integral unit 10to record certain data.

The materials of construction to be employed in the integral pump-valveunit, control rod, delivery pipe, and vertical supports are those whichwill be durable in the presence of the molten metal intended to behandled and which are resistant to erosion and corrosion. When employingmolten magnesium for instance, mild steel or preferably the hightemperature chrome steels such as, for example, 430 stainless aresatisfactory for all surfaces which are to be exposed to the moltenmagnesium. With respect to the valve head 50 and valve seat 46, or anyother member of the apparatus which is to be subjected to precisioncontact and wear at elevated temperatures; the mating surfaces of eitheror both can be provided with a Stellite coating for resistance todeformation and abrasion upon impact when engaging said valve and seat,or, in

the case of said other members, can be constructed com-. pletely ofStellite.

With respect to the impeller shaft 24 and valve stem 54 which aresubjected to considerable stress at elevated temperature; these partsmay also be constructed of tool steel of the conventional 18.4.1composition (about 18 percent tungsten, about 4 percent chromium, andabout 1 percent vanadium, the balance being essentially iron) whichprovides good strength characteristics at the required operatingconditions.

It should be understood that various changes and modification can bemade in the apparatus of the present invention without departing fromthe substance and scope thereof, and it is further understood that thepresent invention is not limited to the embodiment thereof as shown inthe appended drawings.

I claim: An apparatus for the delivery of molten metal to a vutilization device which comprises (1) a submersible incasing, saidcasing having an inlet and outlet means therein, said inlet means havinga longitudinal axis aligned with that of the pump casing, comprising awalled extension attached to the bottom of said pump casing and steppedin from the side walls thereof, said extension having a hemisphericalshape on one side of its minor transverse axis and a hemiellipticalshape on the other side thereof, the wall of the hemielliptical portionextending downwardly such that the major transverse axis of said inletmeans continually reduces itself on the hemielliptical portion thereofuntil equal to the minor transverse axis to form, with the downwardlyextending vertical wall of the hemispherical portion, a circular shapedinlet port such that the axis of the movable valve member of the valveassembly, which is disposed Within the pump casing, is at an acute anglewith respect to the longitudinal axis of said pump casing and crossessaid longitudinal axis of said casing at the inlet part, said valveassembly portion (b) disposed within the pump casing, including a valveseat, a movable valve member, and a control rod,

References Cited by the Examiner UNITED STATES PATENTS 2,625,720 1/1953ROSS 2270 X 2,745,153 5/1956 Burkett 2279 3,074,128 1/1963 Brokel 2270 X3,184,811

5/1965 Bennett et al. 2270 FOREIGN PATENTS 808,444 2/ 1959 GreatBritain.

J. SPENCER OVERHOLSER, Primary Examiner.

said valve member being attached to said control rod; (2) 20 R. S.ANNEAR, Examiner.

